Without limiting the scope of the disclosure, its background is described in connection with carpet recycling.
The problem of carpet recycling, as landfills reach capacity, is reaching a critical stage. One critical problem in the recycling arts today is the problem of waste during recycling processes using basic carpets. The problem becomes exacerbated as newer synthetic polymers and previously recycled materials are used to produce carpet. One unsolved problem in the recycling arts is the challenge that the carpet components are designed to be strongly commingled mechanically and chemically. Due to the strong chemical and mechanical bonding or attachment of the carpet components, useful raw materials that are substantially contaminant-free, ash-free and in a substantially unaltered form following recycling has not been attained.
One method for carpet recycling is taught in U.S. Pat. No. 7,820,728, issued to Wright, et al., which is directed to methods and systems for recycling carpet and carpets manufactured from recycled material. Relevant to the improvements of the present disclosure are the methods for recycling carpet that can recover one or more polymeric carpet components. Specifically, this patent teaches the dissolution of the backing of the polymeric carpet components using certain terpene solvents. However, despite the knowledge of this methodology as of the earliest filing date of this patent in 2006, substantially waste-free carpet recycling is not currently available.
Another such idea is taught in U.S. Pat. No. 5,169,870, issued to Corbin, et al., for reclaiming ε-caprolactam from nylon 6 carpet. The process taught by this patent includes the continuous recovery of ε-caprolactam from a carpet made from nylon 6 and a backing that is inserted into a mechanical separator that prepares scrap-containing nylon 6 and waste. The scrap from the separator is fed to a depolymerizing reactor where the scrap is subjected to a depolymerization catalyst, temperatures of at least the melting point of nylon 6 and superheated steam to produce an ε-caprolactam containing distillate and more waste. The ε-caprolactam in the distillate is said to separate the polymeric components from other volatile agents and is then purified.
Mechanical carpet disruption methods have been taught by a number of patents, including: U.S. Pat. No. 6,610,769, which discloses a method of employing an adhesive that can be completely removed by applying shear in the presence of an aqueous alkaline solution; U.S. Pat. No. 5,240,530, which discloses a method of grinding carpet to a fiber length of less than about one-quarter inch and washing in a water bath to allow the various materials of the carpet to be separated by density; U.S. Pat. No. 5,230,473, which discloses a method for disintegrating, separating, and segregating whole carpet by loosening and debonding the latex/filler binder system by repeated application of highly pressurized fluids such as air, water, heated air, steam, and chemical solutions, and repeated stripping with rotating elements; and U.S. Pat. No. 5,722,603, which discloses a method of recovering face fiber from a carpet employing numerous steps of shredding and impact forces that reduce particle size, separating and washing the particles with screens, followed by separation of the components in water in a hydrocyclone, with the option of using additives that are disrupted by sodium hydroxide and nonionic surfactants.
Despite these various methods and systems for recycling carpet, a need remains for the development of environmentally friendly systems and methods that lead to recycling a majority of the carpet components, with significantly reduced waste, using sustainable compositions and methods, and that yield high quality, clean carpet components that can be completely recycled.